1. Field of the Invention
The present invention relates to a power steering device having a hydraulic cylinder unit that is actuatable in response to turning of a steering wheel for steering an outboard engine mounted on the back of a small boat.
2. Description of the Prior Art
One known power steering device for an outboard engine is disclosed in Japanese laid-open patent publication No. 2-147497 which corresponds to U.S. Pat. No. 4,976,639. The disclosed power steering device has a control cable extending from a steering member, the control cable comprising a core and a sheath. The core is fixed to a bracket on the distal end of a piston rod of a hydraulic cylinder unit that is actuatable to swing the outboard engine in a horizontal direction. The sheath is coupled to a steering tube which is movable with the sheath when the steering member is turned. The movement of the steering tube is transmitted through a gear or a lever to a spool valve, which supplies working oil from a pump into an oil chamber in the hydraulic cylinder unit. The supplied working oil moves the piston rod for swinging a steering arm to steer the outboard engine.
Since the movement of the sheath is transmitted through the steering tube and the gear or lever to the spool valve, the number of parts required is relatively large. An oil seal is required between sliding surfaces of the steering tube and a housing which accommodates the steering tube.